The multimedia card (MMC) is a universal low cost data storage and communication medium. It is designed to cover a wide area of applications such as smart phones, digital cameras, personal digital assistants (PDAs), digital recorders, MP3 players, pagers. Its targeted features include high mobility and high performance at a low cost. High performance can be expressed in terms of low power consumption and high data throughput at the memory card interface.
A conventional multimedia card 10 is illustrated in FIG. 1. The multimedia card 10 can include a flash memory core 12 and a card interface controller 14, which each have a single chip. That is, the multimedia card 10 has two chips. The flash memory core 12 includes a NAND flash memory that is well known in the art. The card interface controller 14 can act as an interface between a host 20 and a flash memory 12 and includes a CPU 31, a ROM 32, an MMC block 33, a buffer RAM 34, and a flash interface block 35. Firmware is stored in the ROM 32 to manage the flash memory 12. The CPU 31 manages the flash memory core 12 using the firmware stored in the ROM 32. The buffer RAM 34 is used as a work RAM and is used to temporarily store data transmitted between the host 20 and the flash memory 12.
An example of the flash memory 12 illustrated in FIG. 1 is discussed in U.S. Pat. No. 5,473,563 entitled “NONVOLATILE SEMICONDUCTOR MEMORY”, which is incorporated herein by reference.
Since the buffer RAM 34 is used as a work RAM, it should have a high capacity (e.g., tens of kilobytes). In a case where a high-capacity buffer RAM and a flash memory 12 are merged into a single chip, an area occupied by the high-capacity buffer RAM 34 is larger than an area of the flash memory 13, i.e., a chip size increases. Further, it may be difficult to fabricate the CPU 31 and the ROM 32 with the flash memory 12.